The intent of this Mentored Research Scientist Development Award is to allow the applicant to develop the research skills necessary to be independent in the investigation of the mechanism underlying poor trunk motor control in individuals with recurrent or chronic low back pain (LBP). The background of the candidate in conjunction with strong mentorship and a dynamic research environment will allow successful completion of the proposed aims. The objectives are to gain a better understanding of how trunk movement and stability are coordinated through sophisticated quantitative methods to provide insight into neuromuscular control strategies. A component of this process will be to determine reliability and responsiveness of our measures of trunk control, and begin to clarify the relationship between poor control, low back pain and therapeutic outcomes. Studies have been designed to test the general hypothesis that, in patients with recurrent and chronic LBP and clinical findings of lumbar instability, altered neuromuscular control strategies are associated with poor movement patterns. Further, these strategies can be improved through rehabilitation. Experiments will be conducted to (1) characterize alterations in neuromuscular control in patients with mechanical LBP, (2) determine the measurement properties of the proposed methods, (3) identify which aspects of trunk neuromuscular control can be improved with therapeutic intervention, and (4) begin to investigate mechanisms underlying improvement in pain and disability with a neuromuscular rehabilitation program. These studies will provide the experiential learning opportunities linked to the didactic plan. This plan is designed to provide new skills in advanced data processing and analysis of kinematic, electromyographic (EMG), and kinetic data that will provide insight into neuromuscular control of functional movements and postural activities. Courses, seminars and directed readings will provide the advanced statistical skills and theoretical background in motor control, neurophysiology, and the effects of chronic pain on movement dysfunction. Direct mentoring and coursework in clinical trial design and management will be the focus of the later studies. Collectively, the experimental outcomes from this grant will have a substantive impact on treatments for patients with mechanical LBP, improve the ability to identify who might respond to this trunk muscle training approach, and provide strategies for reducing the recurrence of low back symptoms.